The present invention relates, in general, to a multi-purpose prefabricated slab, called "Eisekofly-Dalle-Beton-Papier". More specifically, it is a prefabricated reinforced concrete (R.C.) or prestressed reinforced concrete (P.C.) slab with special features that allow it to be used in an easy and advantageous manner compared to known precast slabs.
As is well known, prefabricated two-dimensional structures, known as precast slabs, are usually used to quickly construct slabs.
Such slabs are disclosed in patent documents, such as:
The best known prefabricated slab is the hollow core slab. It is a self-supporting structure, made of concrete with pre-stressed reinforcement made of strands, without shear reinforcement or distribution nets.
The honeycomb slab usually has a width of 120 cm or less and a height between 12 and 70 cm.
Holes are cut into the inside of the honeycomb slab to make the structure lighter.
The honeycomb slab is usually manufactured using an automatic extrusion machine that also creates the lightening holes, the number of which varies depending on the manufacturer and the application requirements.
The most significant problem with the honeycomb slab is precisely the need to use special machines to make it, which increases its cost and, above all, makes it inflexible in terms of size and shape.
Another well-known prefabricated slab type is the 'Predalle' slab, which has a width of 250 cm or less and a height of between 15 and 70 cm.
The 'Predalle' slab is self-supporting and is made of pre-stressed concrete and prestressed reinforcement.
The 'Predalle' slab has reinforcement made of strands and/or slow reinforcement, nets and stirrups. Lightening is achieved by means of polystyrene shapes.
The production of the "Predalle" slab takes place in successive steps on a flat bench, working in layers. As a result, it is not possible to cut holes as in the case of the honeycomb slab, but by means of polystyrene shapes that can have various conformations, although the typical one is rectangular in cross-section.
The biggest problem with the "Predalle" slab is precisely the presence of the polystyrene shapes, which are polluting and not eco-friendly.
In particular, the 'Predalle' slab cannot be used in all those countries where the use of non-eco-compatible materials is prohibited.
For example, in France it is forbidden to use slab whose lightening is realised through the use of materials derived from petroleum.
The purpose of the present invention is to offer a prefabricated slab that is lightened without the aid of polluting lighteners.
Another purpose of the invention is to provide a prefabricated slab that is easily fabricated.
A further purpose of the invention is to provide a prefabricated slab whose mode of construction allows it to be manufactured flexibly, varying in size, shape and characteristics according to the requirements of use.
These and other purposes are achieved, according to the invention, by a prefabricated slab comprising a concrete structure and reinforcement, according to claim 1.
In particular, the prefabricated slab comprises within it at least one lightening element made of a material typically chosen from paper or cardboard or both, said element being capable of creating a volume of lower density than the concrete portion within the prefabricated slab.
In this way, the lightening of the slab according to the invention is achieved without the aid of polystyrene moulds or other petroleum-derived and therefore environmentally unfriendly material.
Advantageously, the one or more lightening elements can be internally filled, so as to avoid any bending or folding.
Alternatively, the one or more lightening elements may be internally hollow, so as to further decrease the weight of the slab of the invention.
Advantageously, one or more lightening elements may have a parallelepiped shape and/or a cylindrical shape depending on the overall volume and dimensions of the prefabricated slab to be lightened.
This reinforcement usually comprises at least one strand or mesh or both. Furthermore, in order to realise a reinforced structure, the prefabricated slab comprises at least one U-shaped member and may comprise at least one strand and/or at least one mesh.
The U-shaped element protrudes from the structure, so as to be a useful coupling element for an eventual casting above the prefabricated slab itself.
The prefabricated slab comprises at least one fastening element useful for lifting the prefabricated slab when it is to be placed in the desired position.
Further features and details can be better understood from the following description, which is given as a non-limiting example, as well as from the accompanying drawing tables in which
With reference to the appended figures, in particular
The precast slab 10 comprises a concrete structure 12 in the shape of a parallelepiped in which strands are embedded.
A lower mesh 16 and an upper mesh 18, both made of a metal alloy, are also embedded in the concrete structure 12 so as to make, together with strands, a reinforcement embedded in the concrete structure 12.
Three parallelepiped lightening elements 20 are included in the concrete structure 12 to lighten the precast slab 10.
In particular, such parallelepiped elements 20 (of which only one is indicated with reference 20) are made entirely of cardboard; in other words, the volume defined by such parallelepiped elements is entirely occupied by cardboard.
Alternatively, such parallelepiped elements 20 may be internally hollow, i.e. made with only the perimeter faces of cardboard.
Furthermore, as illustrated in
Such second U-shaped elements 24 serve to allow for a better coupling with the possible casting arranged above the precast slab 10.
At the four corners of the structure 12 are arranged fastening elements 26 useful for lifting the prefabricated slab 10 when it is to be arranged in the desired position.
According to a second variant of the invention illustrated in
A lower mesh 116 and an upper mesh 118, both of metal alloy, are also embedded in the concrete structure 112, so as to create, together with the strands, a reinforcement embedded in the concrete structure 112.
Included in the concrete structure 112 are six cylindrical lightening elements 120, suitable for lightening the precast slab 110.
In particular, such cylindrical elements 120 (of which only one is indicated by reference 120) are made entirely of cardboard; in other words, the volume defined by such parallelepiped elements is entirely occupied by cardboard.
Alternatively, such cylindrical elements 120 may be internally hollow, i.e. made with only the perimeter faces of cardboard.
Furthermore, as illustrated in
Such second U-shaped elements 124 serve to allow for a better coupling with the possible casting disposed above the precast slab 110.
Fixing elements 126 are arranged at the four corners of the structure 112, which are useful for lifting the prefabricated slab 110 when it is to be arranged in the desired position.
Further variants may also be provided which are to be considered within the scope of the invention.
For example, the shape of the lightening elements may be other than parallelepiped or cylindrical.
In any case, the presence of lightening elements such as parallelepiped elements 20 or cylindrical elements 120 makes it possible to avoid the use of shapes of polystyrene or other petroleum-derived material, while still achieving the desired lightening.
Furthermore, the use of such lightening elements allows the prefabricated slab according to the invention to be made without the use of specific machinery. Thus, it is possible to make the prefabricated slab according to the desired shape, size and characteristics, without constraints due to the use of machinery.
Additionally, the lightening element realised can comprise a containing structure made of paper and/or cardboard inside which is arranged a honeycomb or lattice structure, also typically made of paper and/or cardboard or another nonpolluting material, with the purpose of lightening the slab, but at the same time giving solidity to the lightening element itself.
Alternatively, the honeycomb or lattice structure can be filled with lightening material with a lower density than concrete.
This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.